Tailgate and Brake light help

[spacebiscuit]

I have been wiring my tailgate/brake lights today. When the headlights are switched off and I apply the the brakes the tailgate lights illuminate as expected. But if i turn the headlights on the tailgate lights are bright - as if the brakes have been applied. When i do apply the brakes the tailgate lights do not get any brighter.

The tailgate bulb has two terminals. I have a negative/earth wired to one and i have piggybacked the tailgate onto the brakelight terminal which are both connected to the other terminal. This is likely the issue but I can't see any other way.

Anyone got any ideas?

[busdaddy]

Is "tailgate" an autocorrect Iphoneism?, or a UK term for a car part we call something else in North America?, pickup trucks have tailgates on the rear end of the bed, some call the rear upper hatch a tailgate (the one with a window in it) as well here.

It might be picture time, sounds like you have some wires stirred up or incorrectly earthed.
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[skills@eurocarsplus]

first off.....what year bus?

second (which really doesn't matter) is it usa spec or euro spec?

3rd, even euro spec lights have a terminal riveted to the body of the tail light housing if we are talking early bay (early early has a sharp spike that dug into the body as ground...or earth as you may call it)

sounds to me that you grounded the parking light terminal, and have (by some crazy chance) both of the brighter filaments wired to the brake lights.

you need 3 wires on an early bay tail light, UNLESS it's euro spec.

USA= brake(doubles as turn signal) parking and ground

EURO= brake, parking, turn and ground

so, as BD mentions, we need pix to help
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[spacebiscuit]

Apologies for the confusion, I thought I was using terminology in keeping with the majority here on the Samba.

The bus us a 1972 but it was imported form the States to the UK. This is the diagram I am using:

https://www.thesamba.com/vw/archives/info/wiring/bus_8_71.jpg

Looks like it is referred to as a 'tail' light. My units have a 4 connections:

1. One up top fo rhte turn signal/indicator
2/3. Two on the lower/bigger light
4. Another in the middle of the hosing that doesn't make contact with the prongs and bulbs.

[Xevin]

Try this thread.

https://www.thesamba.com/vw/forum/viewtopic.php?t=...0f4324d892
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[spacebiscuit]

Ok so looking at the thread above my tail light is the same as this but without the back-up lights:

So it looks as if the tail light bulb has the brake lights wired to one of the terminals and the main lights to the other terminal. I thought I had tried this setup and I seem to recall a fuse blowing when I tried the brakes.

What is the 3rd blake wire though?

Seems I should try again, likely something else caused the fuse to blow.

[busdaddy]

[spacebiscuit]

So does the black wire "solid black (small connector) go to the backup light "solid black (big connector)"?

[samwise]

[busdaddy]

No, it won't fit, "small connector" is those skinny spades like you find on the dash light sockets. I have no idea why the wire to the side marker is black, it should be grey/red or grey/black, or even just grey, some color similar to the tail light circuit that connects to the other tab on the same terminal.
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[Xevin]

Spacebicuit. I just loaded up a bunch of photos of my 72 bus tail light replacement in my gallery. The pictures are the original set up before replacement. I used the Arteb Brazilian VW replacement buckets. The Arteb buckets only have the two large terminals for the “Brake and tail light”. Since mine has the two small spades I just split the large terminal post enough to accept the two small spades. The Arteb buckets and lenses still look new 4 years later.
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[spacebiscuit]

[busdaddy]

The tail/brake light is a single bulb with dual filaments, the brake filament is higher wattage then the tail, mix up the wires and you'll never see the brake light when the tail lights are on.
The backup lights are controlled by a switch on the nosecone of the transmission, a black wire runs from coil terminal #15 through an inline fuse holder laying to the left of the engine and then on up to the switch, then another black wire leads back to the lights.
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[ToolBox]

Post up some pictures of the tail lights you have installed on your Bus.

[beetleman217]

I just installed a third brake light and have an electrical oddity. I connected its positive wire to the left brake light terminal with a piggy back connector. Its ground wire is simply screwed into the body. When I engage the brake pedal, the right side brake light and the 3rd brake light come on, but the left brake light (from which the 3rd feeds off of) tuns off! And even more odd, the left backup light comes on! What's going on?

The driving lights are on (excuse the missing left lens)

Brake pedal depressed- WTF?

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If all else fails, stop using all else

1977 Westfalia
1961 Beetle

[Wildthings]

At least part of the problem is going to be a bad ground. Can't say about any wiring you added.

[beetleman217]

Checked the ground, it is solid.

So I assumed the 3rd is "robbing" the left brake light of power, so today I tried something else. I connected the 3rd to BOTH brake lights by means of a cross connection between them, thinking now the right will share some of its power too.

The result was nearly the same - the left brake light (to which the 3rd is connected directly) still goes out, but this time BOTH back up lights came on dimly!

Can anyone suggest where is the right place from which to power the 3rd brake light? Obviously using the brake lights is a no no.

Thanks
_________________
If all else fails, stop using all else

1977 Westfalia
1961 Beetle

[busdaddy]

That ground isn't as "solid" as you think, or the bulb shell isn't making good contact inside the socket, there's nothing wrong with tapping the brake light circuit, you disturbed something while you were F'ng around in there.
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[Wildthings]

Your problem screams a Bad Ground. I would remove the left tail light assembly and polish all the connections and bulb sockets to bare metal and treat them with dielectric grease to prevent further corrosion. I would also replace the ends on the ground wire or make a new ground wire to replace the existing one and make sure the ground connection is shiny metal as well.

[KTPhil]

You have to understand that electricity seeks the ground with the least resistance. So while you may have continuity to ground, it doesn't tell you the resistance and current capacity.. So what can happen is the electricity seeks a better ground through the filaments of one of the other bulbs to IT'S ground, completing the circuit, and lighting another bulb in the process.

So as suggested, remove, clean, and tighten all grounds in the lamp assembly. Next make sure the positive terminals where the bulb connects aren't bent in a say that they short, providing yet another alternate ground path.